Know your caffeine metabolism speed

What to Do

Pay attention to how caffeine affects you personally. If afternoon coffee doesn't seem to bother your sleep, you may be a fast metabolizer. If even morning coffee affects your sleep, you are likely a slow metabolizer. Genetic testing (CYP1A2 gene) can confirm.

Why It Works

Caffeine half-life varies from 2 to 10 hours across individuals due to variations in the CYP1A2 enzyme. Smoking accelerates caffeine metabolism; oral contraceptives and pregnancy slow it. A blanket "no caffeine after 2 PM" rule may be too conservative for fast metabolizers or insufficient for slow ones.

Tips

• 23andMe and similar services report CYP1A2 status as part of their health reports
• About 50% of people are fast metabolizers, 40% intermediate, and 10% slow
• Slow metabolizers also have higher cardiovascular risk from heavy caffeine intake
• If unsure, the conservative 8-10 hour cutoff is the safest default